1. Field of the Invention
The present invention belongs to the field of automatic painting technology, and relates to an explosion-proof device in an automatic painting system.
2. Description of the Prior Art:
Conventional automatic painting systems have painting equipment and other devices placed in a closed painting booth. In operation, the operator is required to work in the painting booth for accomplishing the painting of objects. Accordingly, the various devices in the painting booth are required to be explosion-proof. In addition, the painting booth requires an air conditioning system such as an air curtain system for protecting the operator from paint mist in order to make the working environment safe.
Where the devices in the painting booth are robots, such may require multiple drive mechanisms or actuators as well as means for detecting operative positions. It has been found to be costly to render these actuators and detecting means explosion-proof. The actuator, for example, is required to consist of a hydraulic unit, and an electric control unit for the actuator is complex and large in size.
The inventor has filed U.S. patent application Ser. No. 628,287 on July 6, 1984 for an invention relating to an automatic painting system employing a robot driven by a DC motor. The disclosed invention is essentially concerned with an automatic painting system comprising a painting booth composed of a partition having a door for allowing transfer of a workpiece to be painted into and out of the painting booth and an air inlet port for supplying air into the painting booth to discharge paint mist out of the painting booth, and an electrically operated automatic painting robot comprising an arm having a spray gun, an arm housing accommodating said arm therein and extending through the partition, in a hermetically sealed relation thereto, into the painting booth, and a control unit connected to the arm and disposed outside the painting booth. This arrangement is successful to a certain extent in solving the foregoing problems with the painting system in which the painting devices are housed in the painting booth, that is, the problems of increased size of the overall system due to the large size of the explosion-proof device, associated increased costs, and the like.
However, it has turned out that the earlier invention has the drawback wherein, since the arm of the robot projecting into the painting booth is exposed to a paint mist, paint is deposited on a sliding portion of the arm, imparing the back-and-forth sliding movement of the arm with respect to the arm housing.